Many children with Reversible Obstructive Airway Disease (ROAD) develop acute bronchospasm late during and after strenuous exertion. The causes of the often extreme respiratory distress are not known, and treatment is emperic. The objectives of this research are to identify causal mechanisms and methods of treatment for exercise-induced bronchospasm (EIB). To identify mechanisms, we shall measure respiratory and metabolic adaptations to the exercise and postexercise state in normal children and children with ROAD. Differences in adaptations to exercise will then be investigated for the causes which produced them. The studies will make use of pulmonary function tests and blood analyses to identify changes in airway resistance, gas distribution, ventilatory and mechanical efficiency and metabolic adaptations to exercise. The significance of hyperventilation, acidosis, the anaerobic threshold, lack of physical fitness and postexertional activities in the causation of EIB will be evaluated. The role of the autonomic nervous system and mediator release will be re-investigated by testing the effectiveness of atropine, phentolamine, cromoglycate, aspirin or indomethacin in blocking or lessening the development of EIB. Results from these studies will hopefully identify differences in the physiological adaptations to exercise between children with ROAD and normal children, will demonstrate what mechanisms may be responsible for the development of EIB, and may suggest methods of prevention and therapy of attacks of EIB. Lastly, studies of this kind will also broaden our general understanding of the mechanisms involved in the development of Reversible Obstructive Airway Disease.